Dental articulator

ABSTRACT

Provides frame with mounts with attachment of respective upper and lower dentures, the former suspended from overhead pivoted arm which in denture articulation position can be locked against transverse displacement of upper denture relative to transversely movable lower denture (which is the actual condition in the human mouth). Lower denture is located atop one (or a stack of) ballbearing supported slide plates which permit linear displacement of lower denture in any direction. Consequent vertical oscillation resulting from transverse passage of one denture over cusps of the other, is accommodated by inflatable air chamber which is centrally located above upper denture or else centered below support plate of lower denture and can be inflated by hand bulb to correspond to normal closure pressure previously measured in patient&#39;&#39;s mouth. Adapter plate holding lower denture atop air chamber is also thus capable of small tilting to accommodate vertical self-adjustment. Means also provided to measure transverse displacement of lower denture in each dimension: also to record composite path followed by lower denture. Elimination of pivotal movement of either denture in the articulator, plus fixed rather than customarily movable mounting of upper denture, in conjunction with lower denture movability in all dimensions, results in easier and more satisfactory functional matching of the denture pair.

United States Patent Lawler et al.

[ May 27, 1975 i 1 DENTAL ARTICULATOR [76] Inventors: John K. Lawler, 1740 W. Gardena Blvd; John W. Mitchell, Sr., 170i W. 168th St, both of Los Angeles, Calif. 90247 [22] Filed: Sept. 17, 1973 [2]] Appl. No.: 398,258

Primary Examiner-Robert Peshock Attorney, Agent, or FirmHoward L. Johnson ABSTRACT Provides frame with mounts with attachment of respective upper and lower dentures, the former suspended from overhead pivoted arm which in denture articulation position can be locked against transverse displacement of upper denture relative to transversely movable lower denture (which is the actual condition in the human mouth). Lower denture is located atop one (or a stack of) ballbearing supported slide plates which permit linear displacement of lower denture in any direction. Consequent vertical oscillation resulting from transverse passage of one denture over cusps of the other, is accommodated by inflatable air Chamber which is centrally located above upper denture or else centered below support plate of lower denture and can be inflated by hand bulb to correspond to normal closure pressure previously measured in patients mouth. Adapter plate holding lower denture atop air chamber is also thus capable of small tilting to accommodate vertical self-adjustment. Means also provided to measure transverse displacement of lower denture in each dimension: also to record composite path followed by lower denture. Elimination of pivotal movement of either denture in the articulator, plus fixed rather than customarily movable mounting of upper denture, in conjunction with lower denture movability in all dimensions, results in easier and more satisfac tory functional matching of the denture pair.

20 Claims, 13 Drawing Figures PATENTED W27 5 SHEET 0 2 GF PATENTED MAY 2 71975 SHEET 0 u GF PATENTED 3,885,311

FIG. l2

FIG. l3

DENTAL ARTICIILATOR BACKGROUND OF THE INVENTION Dental articulators are essentially hinged frames in which the technician or dentist mounts a matched upper and lower (usually newly-formed) pair of denturcs so that by movement of one relative to the other. he may check their pattern of movement and ease of articulation and endeavor to correct unevenness or interference that may occur in a functional bite. In the construction of past articulators. effort was made primarily to closelv simulate the pivotal movement of the human jaw. Structurally this took the form of condylar balls and associated guidance slots. (See for example. U.S. Pat. No. 3,l59,9l Such construction attempted to imitate the action of the maxillary ridges in guiding the condylar formations on the human mandible. For convenience, the movable member of the denture pair was usually the upper denture (or more particularly its support frame). but regardless of whether the upper or lower member was adjustable. the effort was always directed toward imitating the manner in which the human jaw moved, rather than primarily reproducing such result, if possible, in another and better way. In retrospect. it was like the early aviation attempts to reproduce the flight pattern of birds by constructing machines which flapped their wings. Mechanically such historic effort was unsuccessful. And the ultimately mechanically successful result i.e., fixed wings and jet engines bore little similarity to any operative or imagined bird; but the result finally obtained. worked better than did the actual birds.

In the present instance, it has been found that a far better dental articulator can be produced by providing one of the dentures (preferably the lower) with linear or planar adjustability along both longitudinal and lateral axes (including any intermediate angular displacement through 360 in such plane), plus resilient upright (perpendicular) seIf-adjustability to accommodate sidewisc (Bennett movement") shift over the cusps. Such construction completely eliminates pivotal movement of one denture relative to the other during their matching in the articulator. Upon reflection, it may be recognised that the pivotal movement of the mandicular or lower jaw in the human mouth is not intended to initiate or create a match of upper or lower dentition, but rather to bring together in a common plane (by pivotal action) already integrated upper and lower sets of teeth which by prior use have formed a functional match. Such matching is not produced by pivotal movement; it is produced by teeth moving across each other along a common plane. Accordingly a pivotal articulation is not a necessary requirement ofa dental articulator.

BRIEF STATEMENT OF THE INVENTION Thus the invention provides an articulator in which pivotal movement about condylar balls ofa denture per se is absent during manipulative adjustment or articulation, and which provides transverse planar movement having a complete range of 360 in a closed path or loop along the plane for one (preferably lower) den ture, achieved by mounting the denture on at least one, ball-bearing supported (generally horizontal) mount or plate. In addition, resilient means are provided, which are aligned crosswise to the upright or perpendicular to such transverse plane or denture axes, so as to accommodate the (vertical) tilting displacement resulting from transverse movement of a tooth over an opposing cusp, Such resilient means may take the form of an inflatable airbag of lesser perimeter than the denture and centrally located along the attachment side of either denture, which chamber can be inflated by a hand bulb or manual pump and by reference to a connected ma nometer (cg, of a range adapted for pulse measurement) can be held at a predetermined pressure (corresponding to the normal pressure maintained by the patient before extraction of his natural teeth).

However. the articulator can be used without inclusion or use of such upright resilient element, simply by allowing free vertical displacement of the upper denture, the force of gravity serving to keep it in contact with the lower denture; or such weight can be added thereto as required.

One form of planar displaceable mount is provided by a stack of horizontal slide plates which are vertically separated by parallel racks of ball bearings of which the racks of one layer are movable in a linear track which is perpendicular to a linear track which carries the racks of ball bearings of another layer, the two upper slide plates thus each being displaceable transversely in a different direction relative to a fixed foundation or bottom plate of the stack. Accordingly, composite movement of the two slide plates can move the lower denture in any direction relative to the upper denture, while still keeping the lower denture in the same plane (except as it may be vertically oscillated or tilted by the resilient means or airbag when the latter underlies the lower denture).

Alternately, planar displacement of a denture and its mount may be effected by a single ball-bearing supported plate which is not restricted by a track to linear movement. Such construction is simpler but may be less easy to guide manually.

Added calibration means enables measurement of the extent of denture movement in each of the three dimensions (i.e., along the longitudinal and transverse axes of the dentures and upright or perpendicular thereto), for purposes of subsequent reproduction of movement in the articulator or for comparison with actual measurement of movement of the patients jaw.

While desired articulation of the pair of dentures is effected without pivotal movement of one mount or denture relative to the other, a practical construction for the articulator secures the upper mount to a hingedly connected, overhanging arm. Consequently means are provided for selectively locking this pivotal arm when in downswung position, so as to retain its denture against both pivotal and transverse displacement, while at the same time permitting upright oscillation (as by compression of the pressurized air bag) in response to transverse movement of the lower denture across contacting cusps. However when the resilient element is associated with the lower denture, the upper mount may also be secured against vertical displace ment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front elevation of the dental articulator with the outswung position of the uppenarm lock bolt shown in broken lines.

FIG. 2 is a vcr'ical sectional view through the stacked trio of lower denture-positioning slide plates, the upper two being vertically separated by supporting racks of ball bearings, viewed along line 2-2 of FIG. 3.

FIG. 3 is a side elevational view of the articulator with the backswung position of the upper arm shown in broken lines.

FIG. 4 is a construction detail of the forward end of the upper arm, partly in elevation and partly in vertical section.

FIG. 5 is a transverse sectional view through the uppermost of the positioning plates, showing the adapter plate and air bag in elevation.

FIG. 6 is a top plan view of the articulator.

FIGS. 7, 8, 9 are schematic plan views of the upper two slide plates of the stack shown in FIG. 2, seen in different relative positions to illustrate their range of movement.

FIG. 10 is an exploded perspective view of the trio of positioning plates and their intervening racks of ball bearings.

FIG. II is a perspective view of ball bearings and base plate associated with a single slide plate of an al ternate construction.

FIG. 12 is an elevational view ofthe lower mount as sembly containing the base plate of FIG. 11 with parts broken away.

FIG. 13 is a detail elevation and vertical section of the forward end of the upper arm, similar to FIG. 4, but modified to include an air bag therein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT In comparing the present articulater with those of the prior art, it should be realized that the latter have consistently used the upper segment, which represents the maxillary jaw. as the primary unit for articulation and adjustment. The mandibular segment was related to this solely or primarily by pivotal relation and was generally incapable of linear vertical adjustability. As long as there was a pivotal coupling of the upper and lower jaws, i.e., dentures it was considered that any resulting articulation would be both "natural" and complete. What was apparently overlooked was that after the jaws are pivotally brought together, the pivotal move ment then plays little or no part in continued chewing. Accordingly, reproducing a patients measured movements on a pivotal frame was not actually reproducing the movement of his muscles and tendons in mastication. When the jaws are closed, the lower jaw follows a more-or-less elliptical or annular pattern in most chewing; and this is related to a fixed upper jaw with the lower jaw held substantially parallel thereto.

The here depicted dental articulator in its simplest form is constructed with a more or-less open frame F which supplies a base plate or foundation for a lower assembly or denture mount M. An overhanging, hinged or pivotally attached arm 32 (so disposed for ease of placing and removing the dentures in the frame), suspends an upper mount U in general vertical alignment with the lower mount when swung to its forward or set position. as seen in solid lines in FIG. 3. The foundation 20 is suspended upon dependent pods or feet 21, 22, 23, 24 located adjacent the respective corners and enabling the articulator to be moved from place to place and located on any convenient table or shelf as desired. Upstanding along the central portion of the rear edge of the foundation is a perpendicular or vertical wall 26, front the upper portion of which a pair of horizontally separated, mutually parallel, triangular bearing ears 28,29 (FIG. 6) project rearward. A transverse cylindrical rod jointly traverses the pair of ears and forms the axle for a generally inverted-U-shape arm 32, the descending forward end 33 of which spacedly overhangs the area of the base plate 20, generally centered above the stacked structure which is supported thereon. A flat ledge 35 forward projecting from the rear upright portion 3! of the arm 32 is disposed to rest upon the top of the rear wall 26. In an edge-opening slot 37 of the end wall is an eye-bolt 38 swingably mounted on a pivot pin 39 so as to be movable between a laterally outswung position (seen in broken lines FIG. 1) and an upright position wherein a terminally-carried lock nut 40 may be tightened down against the upper face of the ledge 35 so as to lodge the arm 32 in its functional or overhanging position; at such time the shaft of the eye-bolt 38 is received in a groove 36 (FIG. 3) of the ledge which is aligned with the slot 37 immediately therebeneath. It will be seen that when the nut 40 is loosened and the bolt 38 swung out of the ledgegroove 36, the arm 32 can be swung back to the position indicated in broken lines in FIG. 3.

Partway up the rear arm 31, the latter is traversed by a cross rod 42, the respective ends of which are sock eted (43) to receive the ends of a conventional face bow (not shown) for occasional use in the event that present articulator users may wish to continue to use such face bow. The intermediate or forward extending portion 34 of the overhanging arm terminally supports the descending portion 33 which is formed with a longitudinal end-opening channel 45 of rectangular cross section. The latter is adapted to receive a correspondingly shaped attachment stem 46 which can be secured by thumbscrew 47 at a selected position of insertion as indicated by calibration lines or indicia 48.

The stem 46 serves to suspend a mounting carrying the upper denture unit U. The latter consists of a fixture or casting 50 (which carries the upstanding stem 46) and a dependently juxtaposed, transverse plate 51, which plate has limited longitudinal adjustability by way of a longitudinal rib or spline 53 slidable along a keyway 52 (FIG. 1) formed in the underface of the casting 50.

A screw 54 (FIG. 6) extends upward from the plate 51 through an elongated slot 55 0f the casting 50 and carries a laterally overlying nut 56 which can thus be tightened against the top of the member 50; the limit of sliding adjustability of the plate 51 is thus defined by the length of the slot 55. The underface of the plate 51 may have tapped apertures 57 for indirect attachment of an upper denture plate D and/or the latter may be temporarily connected by transverse layers of plaster P and wax W. It will be observed that the upper denture is thus firmly anchored for its articulation with the movable lower dentures or plate L which arrangement corresponds to the actual situation occurring in the users mouth.

The lower denture plate L is also fastened by layers of wax W2 and plaster P2 to the top of an adapter plate 60, which plate is vertically traversed by a number of positioning or anchorage pins 61. The adapter plate is located above the base plate 20 by a pile or stack of three similarly rectangular, vertically separated, mutually parallel and generally horizontally disposed shift plates 64, 65, 66 of which the upper two are each hori zontally movable relative to the others as hereafter ex plained, and the lowermost 66 is fixed to the upper face of the base plate by a bolt 67 (FIG. 2) which threadedly engages the tapped aperture 58 of a post 59 which traverses the central opening 62 (FIGv 10) of the bottom plate 66. The anchorage post 59 thence arises through a larger. rectangular opening 63 in the intermediate plate 65 and disposes a flanged head 49 within a bottom socket 44 of the top plate 64. It will be seen that the possible transverse shift of the top plate 64 is limited by the span of the socket 44, and the shift of the intermediate plate 65 is limited by the opening 63.

As seen in FIG. 10, the lowermost plate 66 is formed with a parallel pair of transversely arcuate grooves or tracks 68, 69, spaced inward a small distance from respective opposite parallel edges, which tracks are correspondingly located to similar, complementary grooves 70, 71, formed in the underface of the super posed plate 65. The upper face of the intermediate plate 65 is formed with a similar pair of grooves 72, 73, aligned perpendicular to those of its underface and correspondingly shaped to the pair 74, 75 formed on the underface of the top plate 64. For each complementary pair of grooves there is provided a relatively thin, flat faced, elongated rectangular rack 77, 78, 79, 80, which by means of arcuate surfaced apertures 81, each rack retains a linear row of ball bearings 82. When the respective racks are sandwiched between adjacent plates 64 and 65, or 65 and 66, with the ball bearings in the complementary grooves, the racks themselves do not touch either plate and each plate 64 or 65, individually or jointly, can be easily pushed by hand along the particular grooves in accordance with the patterns indicated in FIGS. 7-9. That is, either plate can be moved by itself or both can be moved simply by pushing the top plate in an angular direction. Alternately, the stack of plates can be locked together by insertion of a cylindrical shaft 84 through the vertically alignable openings 85, 86, 87, which action is particularly desirable when mounting or dismounting a lower denture.

The top plate 64 is formed with a central open-top cavity 90 which is connected to the exterior by a lateral channel 91. Lodged within the chamber is an inflatable air bag 92 connected by a conduit 93 (placed in channel 91) to a gas pressure meter or manometer 94 and hand bulb 95 or other delivery source of compressed air or gas. As seen particularly in FIG. 5, the air bag is centered beneath and directly bears against the undersurface of the adapted plate 60 (which supports the lower denture L) so that the mounted pair of dentures can be pressed together (the upper denture plate D being held immobile by action of the lock nut 40) by a selected air pressure which can be read directly on the manometer 94. Such pressure can be set to equal or approximate that previously measured in the patients mouth before his teeth were extracted, such representing the natural tension of his masticating muscles with jaws lightly clenched.

The forward face of the top plate 64 supports an outward projecting shaft 98 dependently carrying a generally vertical, incisal guide stylus 99, the tip of which is disposed to track or register upon a flat sheet or surface of recording substance (such as paper or wax) which may be placed in a retaining recess 100. The forward face ofthe intermediate plate 65 carries a bracket plate 101 having a dependent arm 102 with a pointer overlying a calibrated index scale 103. By such means, position of the pointer on the scale will show the amount of transverse shift of the intermediate plate (and of the stack-supported lower denture L relative to the fixed upper denture D). In comparison, the path of the stylus 99 records the composite movements of both plates 64, 65 which is the movement imparted to the lower denture.

In addition. an upstanding post 104 centrally located along the forward margin of the base plate 20 between the index scale 103 and the record recess I00 supports a millimeter scale I05 horizontally and rigidly projecting into a front-open recess 106 (without touching same) by means of which calibration the amount of movement of the plate 64 along the longitudinal axis of the denture can be measured. Thus the extremes of transverse movement of the lower denture in each direction, as well as its composite movement (scored on the record surface can be retained for comparison with past or future patterns, or if desired, for reproduction of actual movement measured on the patient.

A further degree of self-adjustability may be achieved by means ofthe lower portions of the adapterplate support pins 61 (FIG. 5) being formed to a loose fit in their respective insertion sockets 4] of the slide plate 64, so that the adapter plate 60 and its supported denture L are capable of a small degree of tipping or tilting as a result of sidewise movement of one denture over cusps of another. Again, such movement corresponds to that actually occurring in a patients mouth, with both natural and false teeth.

The modified construction for a lower denture mount shown in FIGS. 1142 employs a single slide plate 64a with an adapter plate 600 and air bag 920 similar to FIG. 5. A flat-faced base plate 107 is secured to the foundation 20a by a bottom bolt 108 inserted upward into a top-flanged sleeve 109, which sleeve traverses an axial aperture 110 of the plate and penetrates partway into the overlying slide plate 64a by passage through an oversized bore 111 which thus permits transverse displacement of the slide'plate relative to the base plate. The opposing faces of the base plate 107 and slide plate 64a are each formed with a plurality of mutually aligned, annular, complementary recesses 112, 113, each pair of which jointly house a ball bearing 114 of considerably smaller span than the diameter of the recess. The total depth of a pair of recesses, however, is less than the diameter of the contained bearing so that the latter serves to hold the plates separate as well as to enable the upper plate 640 to move in any transverse direction over the base plate. At the same time, the

flanged head 96 of the sleeve 109 holds the two plates together.

The modification shown in FIG. 13 provides an inflatable air chamber 115 housed in a cavity 116 of the forward descending end 33a of the overhanging arm. The air bag rests upon a support disk 117 which is verti cally movable within the chamber in unison with a stem 117 and piston 118, the latter being secured to an attachment block 119 which thus suspends the mount U2 for the upper denture. It will be seen that although the hinged or pivotally mounted arm 34 is locked (by eyebolt 38 and nut 40), the upper denture or its whole mounting assembly is capable of limited vertical adjustability by movement of the piston 118 in its chamber 120.

While the resilient, upright, self-adjusting means is here exemplified by the convenient form of an inflatable and compressible gas chamber (air bag), it will be reali7ed that other equivalent elements could be substi tuted therefor such as springs, torsion bars, etc, Similarly roller bearings could be used in place of the racks of ball bearings between the slide plates, etc.

We claim:

I. A dental articulator characterized by opposing mounts adapted to dispose respective upper and lovvcr dentures in functional positions of mutual engagement, one ofwhich mounts may be secured against lateral displacement while the opposing mount is held upon a plate which is adapted for transverse linear displace ment within an area encompassed by a closed path lying along the plane of mutual engagement,

and means for sclt aligning upright oscillation of said plate by tilting transverse to a generally central axis through said dentures perpendicular to said plane of mutual engagement, in response to said lateral displacement, which displacement causes said ciliation by movement of one denture transverse to the cusps of the other.

2. An articulator according to claim 1 wherein said self-aligning means comprises reilient means.

3. An articulator according to claim 1 wherein said self-aligning means comprises an inflatable gas chamber.

4. An articulator according to claim 1 wherein said linearly displaceable mount comprises a ball-bearing supported slide plate.

5. An articulator according to claim 1 wherein said linearly displaceable mount supports a lower denture and comprises a stacked pair of ball-bearing supported slide plates, adapted for joint movement, and each hav ing guide means for transverse movement in a different direction.

6. An articulator according to claim 5 wherein opposing faces of said slide plates are formed with complementary linear tracks and including longitudinal racks of spaced ball-bearings carried by said racks in said tracks and separating said plates.

7. An articulator according to claim 6 which includes calibrated means for indicating the linear displacement ofeach of said pair of slide plates in its respective direction.

8. An articulator according to claim 1 which includes tracking means for recording the composite path followed by said lateral displacement of a denture.

9. An articulator according to claim 2 wherein said resilient means includes measurable means for holding the pair of dentures in mutual engagement with a selected amount of force.

10. An articulator according to claim 2 wherein said lower mount includes a ball-bearing supported slide plate and said lower denture is mountable upon an up right-adjustable plate having said resilient means dis posed centrally thereto and of lesser perimeter than said denture.

11. An artieulator according to claim 10 wherein said resilient means comprises an inflatable gas chamber, and including gas pressure-measuring means and manually operable means for varying the gas pressure within said chamber.

12. An articulator according to claim 10 wherein said resiliently supported adapter plate is tiltable in response to transverse movement of the lower denture across cusps of the upper denture.

13. An articulator according to claim 11 wherein said lower mount includes a stacked pair of hall-bearing supported slide plates adapted for joint movement within the area of said closed path. said plates being formed with complementary linear tracks respectively between theirjuxtaposed faces and between the underface ofthe lower moveable plate and a base plate thereheneath. said tracks forming guide means for trans verse displacement ofthe plates in different directions, longitudinal racks carrying spaced hall-bearings disposed in each pair of complementary tracks and separating the adjacent plates from each other and from the intervening racks,

[4. A dental articulator comprising a frame carrying a mounting plate for a lower denture and an overhead arm pivotally connected to the frame and carrying a mount for an upper denture which is disposable in functional engagement with said lower denture,

means for selectively locking said upper mount against transverse displacement when the dentures are thus engaged,

said lower mounting plate being supported upon ball bearing means adapted for transverse linear displacement within an area encompassed by a closed path lying along the plane of said functional engagement,

and means for sell aligning upright oscillation of one of said engaged mounts by tilting transverse to a generally central axis through said dentures perpendicular to said plane of functional engagement in response to said lateral displacement, which displacement causes said oscillation by movement of one denture transverse to the cusps of the other.

15. An articulator according to claim 14 wherein said self-aligning means comprises an inflatable gas cham her.

16. An articulator according to claim 15 which includes gas pressure measuring means and manually operable means for varying the gas pressure within said chamber.

17. An articulator according to claim 15 which includes an upright-adjustable and tiltable adapter plate carried by said self-aligning means and supporting said lower denture.

18. An articulator according to claim 15 wherein said lower mount includes a stacked pair of ball-bearing supported slide plates, adapted for joint movement within the area of said closed path, said plates being formed with complementary linear tracks respectively between their juxtaposed faces and between the underface of the lower plate and a base plate therebeneath, said tracks forming guide means for transverse displacement of the plates in different directions, longitudinal racks carrying spaced hall-bearings disposed in each pair of complementary tracks and separating the adjacent plates from each other and from the intervening racks.

19. An articulator according to claim 18 which includes calibrated means for indicating the linear displacement of each of said pair of slide plates in its respective direction.

20. An articulator according to claim 18 which includes gas pressure measuring means and manually operable means for varying the gas pressure within said chamber, 

1. A dental articulator characterized by opposing mounts adapted to dispose respective upper and lower dentures in functional positions of mutual engagement, one of which mounts may be secured against lateral displacement while the opposing mount is held upon a plate which is adapted for transverse linear displacement within an area encompassed by a closed path lying along the plane of mutual engagement, and means for self-aligning upright oscillation of said plate by tilting transverse to a generally central axis through said dentures perpendicular to said plane of mutual engegement, in response to said lateral displacement, which displacement causes said oscillation by movement of one denture transverse to the cusps of the other.
 2. An articulator according to claim 1 wherein said self-aligning means comprises reilient means.
 3. An articulator according to claim 1 wherein said self-aligning means comprises an inflatable gas chamber.
 4. An articulator according to claim 1 wherein said linearly displaceable mount comprises a ball-bearing supported slide plate.
 5. An articulator according to claim 1 wherein said linearly displaceable mount supports a lower denture and comprises a stacked pair of ball-bearing supported slide plates, adapted for joint movement, and each having guide means for transverse movement in a different direction.
 6. An articulator according to claim 5 wherein opposing faces of said slide plates are formed with complementary linear tracks and including longitudinal racks of spaced ball-bearings carried by said racks in said tracks and separating said plates.
 7. An articulator according to claim 6 which includes calibrated means for indicating the linear displacement of each of said pair of slide plates in its respective direction.
 8. An articulator according to claim 1 which includes tracking means for recording the composite path followed by said lateral displacement of a denture.
 9. An articulator according to claim 2 wherein said resilient means includes measurable means for holding the pair of dentures in mutual engagement with a selected amount of force.
 10. An articulator according to claim 2 wherein said lower mount includes a ball-bearing supported slide plate and said lower denture is mountable upon an upright-adjustable plate having said resilient means disposed centrally thereto and of lesser perimeter than said denture.
 11. An articulator according to claim 10 wherein said resilient means comprises an inflatable gas chamber, and including gas pressure measuring means and manually operable means for varying the gas pressure within said chamber.
 12. An articulator according to claim 10 wherein said resiliently supported adapter plate is tiltable in response to transverse movement of the lower denture across cusps of the upper denture.
 13. An articulator according to claim 11 wherein said lower mount includes a stacked pair of ball-bearing supported slide plates, adapted for joint movement within the area of said closed path, said plates being formed with complementary linear tracks respectively between their juxtaposed faces and between the underface of the lower moveable plate and a base plate therebeneath, said tracks forming guide means for transverse displacement of the plates in different directions, longitudinal racks carrying spaced ball-bearings disposed in each pair of complementary tracks and separating the adjacent plates from each other and from the intervening racks.
 14. A dental articulator comprising a frame carrying a mounting plate for a lower denture and an overhead arm pivotally connected to the frame and carrying a mount for an upper denture which is disposable in functional engagement with said lower denture, means for selectively locking said upper mount against transverse displacement when the dentures are thus engaged, said lower mounting plate being supported upon ball-bearing means adapted for transverse linear displacement within an area encompassed by a closed path lying along the plane of said functional engagement, and means for self-aligning upright oscillation of one of said engaged mounts by tilting transverse to a generally central axis through said dentures perpendicular to said plane of functional engagement in response to said lateral displacement, which displacement causes said oscillation by movement of one denture transverse to the cusps of the other.
 15. An articulator according to claim 14 wherein said self-aligning means comprises an inflatable gas chamber.
 16. An articulator according to claim 15 which includes gas pressure measuring means and manually operable means for varying the gas pressure within said chamber.
 17. An articulator according to claim 15 which includes an upright-adjustable and tiltable adapter plate carried by said self-aligning means and supporting said lower denture.
 18. An articulator according to claim 15 wherein said lower mount includes a stacked pair of ball-bearing supported slide plates, adapted for joint movement within the area of said closed path, said plates being formed with complementary linear tracks respectively between their juxtaposed faces and between the underface of the lower plate and a base plate therebeneath, said tracks forming guide means for transverse displacemeNt of the plates in different directions, longitudinal racks carrying spaced ball-bearings disposed in each pair of complementary tracks and separating the adjacent plates from each other and from the intervening racks.
 19. An articulator according to claim 18 which includes calibrated means for indicating the linear displacement of each of said pair of slide plates in its respective direction.
 20. An articulator according to claim 18 which includes gas pressure measuring means and manually operable means for varying the gas pressure within said chamber. 